In a typical multi-strand, reciprocating cold tube reducing mill or the like, there is conventionally provided a large, heavy mill housing, which forms a tunnel-like opening disposed along the desired pass line of the work. A roll carriage is located in said tunnel-like opening and is arranged, by means of an extremely heavy duty crank drive, to be reciprocated in the direction of the pass line axis. The roll carriage mounts a pair of reducing rolls, typically in a four-high arrangement, with the backing rolls engaging the upper and lower walls of the main housing. A stock reducing operation commences with the roll carriage in an upstream position, being drawn in a downstream direction by means of the main driving crank. The working rolls and the backing rolls are geared together, and the backing rolls are connected by a rack to the main housing, so that movement of the carriage results in positive, synchronous rotation of the working rolls over the stock. In a single operating stroke, the tapered grooves of the working rolls serve to reduce a limited length of the workpiece to the desired dimensions, whereupon the working rolls are opened up and the roll carriage is reciprocated back in an upstream direction, without working contact with the stock, to commence a new operating stroke.
To enable the working rolls to disengage the stock, in preparation for a return stroke, positioning wedges are provided above and below the backing plates for the respective upper and lower working rolls. At the commencement of the return stroke, these wedges are withdrawn, releasing the backing plates and permitting limited separation of the working rolls. As will be understood, the manipulation of the backing wedges must be timed with the movements of the carriage, such that the wedges are withdrawn near the downstream end of the crank movement, and reinserted into operating position at the upstream end of the crank stroke. Heretofore, it has been conventional to utilize heavy cam and toggle arrangements for this purpose. These mechanisms, although serviceable, present certain problems with respect to the frequency of maintenance and repair, and also impose certain limitations upon the speed of operation of the system as a whole.
As a basic objective of the invention, a new and improved wedge drive system is provided, which enables the roll positioning wedges to be operated synchronously with the main drive crank but in an intermittent manner, providing a reliable and effective, low maintenance drive system, which is less expensive to construct and maintain than a conventional mechanism and yet which permits higher operating speeds to be realized in the system as a whole. More specifically, in this connection, the movable positioning wedges are arranged to be retracted from and inserted into roll backing position by means of individual rotary eccentric shaft means for each wedge, these individual eccentric shafts are provided with rugged support bearings, to withstand the forces necessary to extract and reinsert the roll backing wedges.
As another significant feature of the invention, the eccentric drive shafts for the roll backing wedges are arranged to be driven through a Geneva-like index drive, the input to which is a constant rotation, as a function of the main drive system, whereas the output is an intermittent rotation, limited both as to angle of rotation and as to time. Thus, at the end of the downstream stroke of the main drive crank, the intermittent drive mechanism functions to rotate the wedge drive eccentrics through one half revolution, to extract the roll positioning wedges and permit separation of the rolls. As the roll carriage is returned to the upstream limit position, a further operation of the indexing drive occurs, to rotate the eccentric shafts through a second one half revolution, to reinsert the roll positioning wedges into their operating positions. The use of an intermittently indexing drive, operated directly from the main crank drive, greatly simplifies the mechanisms of the wedge drive, enabling simpler, more rugged wedge drives to be provided at lower cost than conventional mechanisms.
For a better understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description and to the accompanying drawings.